Production of high purity thorium oxide from complex ores leach liquor

Abstract

This paper investigates a method for separation and purification of thorium from leach liquors that contains thorium and rare-earth elements. In this study, Fe removal was optimized with Adogen 464 before the extraction of thorium. Thorium was extracted with 30% D2EHPA-in kerosene with a 1/3 organic/aqueous ratio. Stoichiometry of the thorium-D2EHPA complex was calculated as 1:2.6 from slope analysis. After extraction, LREEs and HREEs were scrubbed from the loaded organic with 0.25 M H2SO4 and 6 M HCl, respectively. Scrubbed organic was stripped with 6 M H2SO4. Thorium oxalate was precipitated by oxalic acid and calcined at 1050 °C. After calcination, the purity of thorium oxide was 99.23% according to ICP-OES.